The blazing hazard Carl imagines falling into if Donut casts a fire-flavored War Crime and the Nest collapses.
Weighing what happens if Donut casts a fire version of War Crime while the Anti-Escape Trap Net still seals the tower, Carl reaches a grim conclusion about himself: with no Hover and no way to jump, he would ride the Nest down into a Wall of Fire filled with fleshers.
That image is what drives his frantic order — cast the spell, since Li Na has already refused the abort and the Rolling Battle Formation Ball is breaking, but pick anything except fire, so the Nest stays intact long enough for both of them to survive.
A sheet of flame filling the ground around the tower's base.
The fatal outcome Carl is trying to avoid by banning fire from the War Crime cast.
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